-- https://github.com/Tieske/date
---------------------------------------------------------------------------------------
-- Module for date and time calculations
--
-- Version 2.1.1
-- Copyright (C) 2006, by Jas Latrix (jastejada@yahoo.com)
-- Copyright (C) 2013-2014, by Thijs Schreijer
-- Licensed under MIT, http://opensource.org/licenses/MIT

--[[ CONSTANTS ]] --
local HOURPERDAY = 24
local MINPERHOUR = 60
local MINPERDAY = 1440 -- 24*60
local SECPERMIN = 60
local SECPERHOUR = 3600 -- 60*60
local SECPERDAY = 86400 -- 24*60*60
local TICKSPERSEC = 1000000
local TICKSPERDAY = 86400000000
local TICKSPERHOUR = 3600000000
local TICKSPERMIN = 60000000
local DAYNUM_MAX = 365242500 -- Sat Jan 01 1000000 00:00:00
local DAYNUM_MIN = -365242500 -- Mon Jan 01 1000000 BCE 00:00:00
local DAYNUM_DEF = 0 -- Mon Jan 01 0001 00:00:00
local _;
--[[ LOCAL ARE FASTER ]] --
local type = type
local pairs = pairs
local error = error
local assert = assert
local tonumber = tonumber
local tostring = tostring
local string = string
local math = math
local os = os
local unpack = unpack or table.unpack
local pack = table.pack or function(...) return { n = select('#', ...), ... } end
local setmetatable = setmetatable
local getmetatable = getmetatable
--[[ EXTRA FUNCTIONS ]] --
local fmt = string.format
local lwr = string.lower
local upr = string.upper
local rep = string.rep
local len = string.len
local sub = string.sub
local gsub = string.gsub
local gmatch = string.gmatch or string.gfind
local find = string.find
local ostime = os.time
local osdate = os.date
local floor = math.floor
local ceil = math.ceil
local abs = math.abs
-- removes the decimal part of a number
local function fix(n) n = tonumber(n) return n and ((n > 0 and floor or ceil)(n)) end

-- returns the modulo n % d;
local function mod(n, d) return n - d * floor(n / d) end

-- rounds a number;
local function round(n, d) d = d ^ 10 return floor((n * d) + .5) / d end

-- rounds a number to whole;
local function whole(n) return floor(n + .5) end

-- is `str` in string list `tbl`, `ml` is the minimun len
local function inlist(str, tbl, ml, tn)
    local sl = len(str)
    if sl < (ml or 0) then return nil end
    str = lwr(str)
    for k, v in pairs(tbl) do
        if str == lwr(sub(v, 1, sl)) then
            if tn then tn[0] = k end
            return k
        end
    end
end

local function fnil() end

local function fret(x) return x; end

--[[ DATE FUNCTIONS ]] --
local DATE_EPOCH -- to be set later
local sl_weekdays = {
    [0] = "Sunday",
    [1] = "Monday",
    [2] = "Tuesday",
    [3] = "Wednesday",
    [4] = "Thursday",
    [5] = "Friday",
    [6] = "Saturday",
    [7] = "Sun",
    [8] = "Mon",
    [9] = "Tue",
    [10] = "Wed",
    [11] = "Thu",
    [12] = "Fri",
    [13] = "Sat",
}
local sl_meridian = { [-1] = "AM", [1] = "PM" }
local sl_months = {
    [00] = "January",
    [01] = "February",
    [02] = "March",
    [03] = "April",
    [04] = "May",
    [05] = "June",
    [06] = "July",
    [07] = "August",
    [08] = "September",
    [09] = "October",
    [10] = "November",
    [11] = "December",
    [12] = "Jan",
    [13] = "Feb",
    [14] = "Mar",
    [15] = "Apr",
    [16] = "May",
    [17] = "Jun",
    [18] = "Jul",
    [19] = "Aug",
    [20] = "Sep",
    [21] = "Oct",
    [22] = "Nov",
    [23] = "Dec",
}
-- added the '.2'  to avoid collision, use `fix` to remove
local sl_timezone = {
    [000] = "utc",
    [0.2] = "gmt",
    [300] = "est",
    [240] = "edt",
    [360] = "cst",
    [300.2] = "cdt",
    [420] = "mst",
    [360.2] = "mdt",
    [480] = "pst",
    [420.2] = "pdt",
}
-- set the day fraction resolution
local function setticks(t)
    TICKSPERSEC = t;
    TICKSPERDAY = SECPERDAY * TICKSPERSEC
    TICKSPERHOUR = SECPERHOUR * TICKSPERSEC
    TICKSPERMIN = SECPERMIN * TICKSPERSEC
end

-- is year y leap year?
local function isleapyear(y) -- y must be int!
return (mod(y, 4) == 0 and (mod(y, 100) ~= 0 or mod(y, 400) == 0))
end

-- day since year 0
local function dayfromyear(y) -- y must be int!
return 365 * y + floor(y / 4) - floor(y / 100) + floor(y / 400)
end

-- day number from date, month is zero base
local function makedaynum(y, m, d)
    local mm = mod(mod(m, 12) + 10, 12)
    return dayfromyear(y + floor(m / 12) - floor(mm / 10)) + floor((mm * 306 + 5) / 10) + d - 307
    --local yy = y + floor(m/12) - floor(mm/10)
    --return dayfromyear(yy) + floor((mm*306 + 5)/10) + (d - 1)
end

-- date from day number, month is zero base
local function breakdaynum(g)
    local g = g + 306
    local y = floor((10000 * g + 14780) / 3652425)
    local d = g - dayfromyear(y)
    if d < 0 then y = y - 1; d = g - dayfromyear(y) end
    local mi = floor((100 * d + 52) / 3060)
    return (floor((mi + 2) / 12) + y), mod(mi + 2, 12), (d - floor((mi * 306 + 5) / 10) + 1)
end

--[[ for floats or int32 Lua Number data type
local function breakdaynum2(g)
  local g, n = g + 306;
  local n400 = floor(g/DI400Y);n = mod(g,DI400Y);
  local n100 = floor(n/DI100Y);n = mod(n,DI100Y);
  local n004 = floor(n/DI4Y);   n = mod(n,DI4Y);
  local n001 = floor(n/365);   n = mod(n,365);
  local y = (n400*400) + (n100*100) + (n004*4) + n001  - ((n001 == 4 or n100 == 4) and 1 or 0)
  local d = g - dayfromyear(y)
  local mi = floor((100*d + 52)/3060)
  return (floor((mi + 2)/12) + y), mod(mi + 2,12), (d - floor((mi*306 + 5)/10) + 1)
end
]]
-- day fraction from time
local function makedayfrc(h, r, s, t)
    return ((h * 60 + r) * 60 + s) * TICKSPERSEC + t
end

-- time from day fraction
local function breakdayfrc(df)
    return
    mod(floor(df / TICKSPERHOUR), HOURPERDAY),
    mod(floor(df / TICKSPERMIN), MINPERHOUR),
    mod(floor(df / TICKSPERSEC), SECPERMIN),
    mod(df, TICKSPERSEC)
end

-- weekday sunday = 0, monday = 1 ...
local function weekday(dn) return mod(dn + 1, 7) end

-- yearday 0 based ...
local function yearday(dn)
    return dn - dayfromyear((breakdaynum(dn)) - 1)
end

-- parse v as a month
local function getmontharg(v)
    local m = tonumber(v);
    return (m and fix(m - 1)) or inlist(tostring(v) or "", sl_months, 2)
end

-- get daynum of isoweek one of year y
local function isow1(y)
    local f = makedaynum(y, 0, 4) -- get the date for the 4-Jan of year `y`
    local d = weekday(f)
    d = d == 0 and 7 or d -- get the ISO day number, 1 == Monday, 7 == Sunday
    return f + (1 - d)
end

local function isowy(dn)
    local w1;
    local y = (breakdaynum(dn))
    if dn >= makedaynum(y, 11, 29) then
        w1 = isow1(y + 1);
        if dn < w1 then
            w1 = isow1(y);
        else
            y = y + 1;
        end
    else
        w1 = isow1(y);
        if dn < w1 then
            w1 = isow1(y - 1)
            y = y - 1
        end
    end
    return floor((dn - w1) / 7) + 1, y
end

local function isoy(dn)
    local y = (breakdaynum(dn))
    return y + (((dn >= makedaynum(y, 11, 29)) and (dn >= isow1(y + 1))) and 1 or (dn < isow1(y) and -1 or 0))
end

local function makedaynum_isoywd(y, w, d)
    return isow1(y) + 7 * w + d - 8 -- simplified: isow1(y) + ((w-1)*7) + (d-1)
end

--[[ THE DATE MODULE ]] --
local fmtstr = "%x %X";
--#if not DATE_OBJECT_AFX then
local date = {}
setmetatable(date, date)
-- Version:  VMMMRRRR; V-Major, M-Minor, R-Revision;  e.g. 5.45.321 == 50450321
date.version = 20010001 -- 2.1.1
--#end -- not DATE_OBJECT_AFX
--[[ THE DATE OBJECT ]] --
local dobj = {}
dobj.__index = dobj
dobj.__metatable = dobj
-- shout invalid arg
local function date_error_arg() return error("invalid argument(s)", 0) end

-- create new date object
local function date_new(dn, df)
    return setmetatable({ daynum = dn, dayfrc = df }, dobj)
end

-- is `v` a date object?
local function date_isdobj(v)
    return (type(v) == 'table' and getmetatable(v) == dobj) and v
end

--#if not NO_LOCAL_TIME_SUPPORT then
-- magic year table
local date_epoch, yt;
local function getequivyear(y)
    assert(not yt)
    yt = {}
    local de, dw, dy = date_epoch:copy()
    for i = 0, 3000 do
        de:setyear(de:getyear() + 1, 1, 1)
        dy = de:getyear()
        dw = de:getweekday() * (isleapyear(dy) and -1 or 1)
        if not yt[dw] then yt[dw] = dy end --print(de)
        if yt[1] and yt[2] and yt[3] and yt[4] and yt[5] and yt[6] and yt[7] and yt[-1] and yt[-2] and yt[-3] and yt[-4] and yt[-5] and yt[-6] and yt[-7] then
            getequivyear = function(y) return yt[(weekday(makedaynum(y, 0, 1)) + 1) * (isleapyear(y) and -1 or 1)] end
            return getequivyear(y)
        end
    end
end

-- TimeValue from daynum and dayfrc
local function dvtotv(dn, df)
    return fix(dn - DATE_EPOCH) * SECPERDAY + (df / 1000)
end

-- TimeValue from date and time
local function totv(y, m, d, h, r, s)
    return (makedaynum(y, m, d) - DATE_EPOCH) * SECPERDAY + ((h * 60 + r) * 60 + s)
end

-- TimeValue from TimeTable
local function tmtotv(tm)
    return tm and totv(tm.year, tm.month - 1, tm.day, tm.hour, tm.min, tm.sec)
end

-- Returns the bias in seconds of utc time daynum and dayfrc
local function getbiasutc2(self)
    local y, m, d = breakdaynum(self.daynum)
    local h, r, s = breakdayfrc(self.dayfrc)
    local tvu = totv(y, m, d, h, r, s) -- get the utc TimeValue of date and time
    local tml = osdate("*t", tvu) -- get the local TimeTable of tvu
    if (not tml) or (tml.year > (y + 1) or tml.year < (y - 1)) then -- failed try the magic
    y = getequivyear(y)
    tvu = totv(y, m, d, h, r, s)
    tml = osdate("*t", tvu)
    end
    local tvl = tmtotv(tml)
    if tvu and tvl then
        return tvu - tvl, tvu, tvl
    else
        return error("failed to get bias from utc time")
    end
end

-- Returns the bias in seconds of local time daynum and dayfrc
local function getbiasloc2(daynum, dayfrc)
    local tvu
    -- extract date and time
    local y, m, d = breakdaynum(daynum)
    local h, r, s = breakdayfrc(dayfrc)
    -- get equivalent TimeTable
    local tml = { year = y, month = m + 1, day = d, hour = h, min = r, sec = s }
    -- get equivalent TimeValue
    local tvl = tmtotv(tml)

    local function chkutc()
        tml.isdst = nil; local tvug = ostime(tml) if tvug and (tvl == tmtotv(osdate("*t", tvug))) then tvu = tvug return end
        tml.isdst = true; local tvud = ostime(tml) if tvud and (tvl == tmtotv(osdate("*t", tvud))) then tvu = tvud return end
        tvu = tvud or tvug
    end

    chkutc()
    if not tvu then
        tml.year = getequivyear(y)
        tvl = tmtotv(tml)
        chkutc()
    end
    return ((tvu and tvl) and (tvu - tvl)) or error("failed to get bias from local time"), tvu, tvl
end

--#end -- not NO_LOCAL_TIME_SUPPORT

--#if not DATE_OBJECT_AFX then
-- the date parser
local strwalker = {} -- ^Lua regular expression is not as powerful as Perl$
strwalker.__index = strwalker
local function newstrwalker(s) return setmetatable({ s = s, i = 1, e = 1, c = len(s) }, strwalker) end

function strwalker:aimchr() return "\n" .. self.s .. "\n" .. rep(".", self.e - 1) .. "^" end

function strwalker:finish() return self.i > self.c end

function strwalker:back() self.i = self.e return self end

function strwalker:restart() self.i, self.e = 1, 1 return self end

function strwalker:match(s) return (find(self.s, s, self.i)) end

function strwalker:__call(s, f) -- print("strwalker:__call "..s..self:aimchr())
local is, ie; is, ie, self[1], self[2], self[3], self[4], self[5] = find(self.s, s, self.i)
if is then self.e, self.i = self.i, 1 + ie; if f then f(unpack(self)) end return self end
end

local function date_parse(str)
    local y, m, d, h, r, s, z, w, u, j, e, k, x, v, c, chkfin, dn, df;
    local sw = newstrwalker(gsub(gsub(str, "(%b())", ""), "^(%s*)", "")) -- remove comment, trim leading space
    --local function error_out() print(y,m,d,h,r,s) end
    local function error_dup(q) --[[error_out()]] error("duplicate value: " .. (q or "") .. sw:aimchr()) end

    local function error_syn(q) --[[error_out()]] error("syntax error: " .. (q or "") .. sw:aimchr()) end

    local function error_inv(q) --[[error_out()]] error("invalid date: " .. (q or "") .. sw:aimchr()) end

    local function sety(q) y = y and error_dup() or tonumber(q); end

    local function setm(q) m = (m or w or j) and error_dup(m or w or j) or tonumber(q) end

    local function setd(q) d = d and error_dup() or tonumber(q) end

    local function seth(q) h = h and error_dup() or tonumber(q) end

    local function setr(q) r = r and error_dup() or tonumber(q) end

    local function sets(q) s = s and error_dup() or tonumber(q) end

    local function adds(q) s = s + tonumber(q) end

    local function setj(q) j = (m or w or j) and error_dup() or tonumber(q); end

    local function setz(q) z = (z ~= 0 and z) and error_dup() or q end

    local function setzn(zs, zn) zn = tonumber(zn); setz(((zn < 24) and (zn * 60) or (mod(zn, 100) + floor(zn / 100) * 60)) * (zs == '+' and -1 or 1)) end

    local function setzc(zs, zh, zm) setz(((tonumber(zh) * 60) + tonumber(zm)) * (zs == '+' and -1 or 1)) end

    if not (sw("^(%d%d%d%d)", sety) and (sw("^(%-?)(%d%d)%1(%d%d)", function(_, a, b) setm(tonumber(a)); setd(tonumber(b)) end) or sw("^(%-?)[Ww](%d%d)%1(%d?)", function(_, a, b) w, u = tonumber(a), tonumber(b or 1) end) or sw("^%-?(%d%d%d)", setj) or sw("^%-?(%d%d)", function(a) setm(a); setd(1) end))
            and ((sw("^%s*[Tt]?(%d%d):?", seth) and sw("^(%d%d):?", setr) and sw("^(%d%d)", sets) and sw("^(%.%d+)", adds))
            or sw:finish() or (sw "^%s*$" or sw "^%s*[Zz]%s*$" or sw("^%s-([%+%-])(%d%d):?(%d%d)%s*$", setzc) or sw("^%s*([%+%-])(%d%d)%s*$", setzn))))
    then --print(y,m,d,h,r,s,z,w,u,j)
    sw:restart(); y, m, d, h, r, s, z, w, u, j = nil;
    repeat -- print(sw:aimchr())
        if sw("^[tT:]?%s*(%d%d?):", seth) then --print("$Time")
        _ = sw("^%s*(%d%d?)", setr) and sw("^%s*:%s*(%d%d?)", sets) and sw("^(%.%d+)", adds)
        elseif sw("^(%d+)[/\\%s,-]?%s*") then --print("$Digits")
        x, c = tonumber(sw[1]), len(sw[1])
        if (x >= 70) or (m and d and (not y)) or (c > 3) then
            sety(x + ((x >= 100 or c > 3) and 0 or 1900))
        else
            if m then setd(x) else m = x end
        end
        elseif sw("^(%a+)[/\\%s,-]?%s*") then --print("$Words")
        x = sw[1]
        if inlist(x, sl_months, 2, sw) then
            if m and (not d) and (not y) then d, m = m, false end
            setm(mod(sw[0], 12) + 1)
        elseif inlist(x, sl_timezone, 2, sw) then
            c = fix(sw[0]) -- ignore gmt and utc
            if c ~= 0 then setz(c, x) end
        elseif inlist(x, sl_weekdays, 2, sw) then
            k = sw[0]
        else
            sw:back()
            -- am pm bce ad ce bc
            if sw("^([bB])%s*(%.?)%s*[Cc]%s*(%2)%s*[Ee]%s*(%2)%s*") or sw("^([bB])%s*(%.?)%s*[Cc]%s*(%2)%s*") then
                e = e and error_dup() or -1
            elseif sw("^([aA])%s*(%.?)%s*[Dd]%s*(%2)%s*") or sw("^([cC])%s*(%.?)%s*[Ee]%s*(%2)%s*") then
                e = e and error_dup() or 1
            elseif sw("^([PApa])%s*(%.?)%s*[Mm]?%s*(%2)%s*") then
                x = lwr(sw[1]) -- there should be hour and it must be correct
                if (not h) or (h > 12) or (h < 0) then return error_inv() end
                if x == 'a' and h == 12 then h = 0 end -- am
                if x == 'p' and h ~= 12 then h = h + 12 end -- pm
            else error_syn()
            end
        end
        elseif not (sw("^([+-])(%d%d?):(%d%d)", setzc) or sw("^([+-])(%d+)", setzn) or sw("^[Zz]%s*$")) then -- sw{"([+-])",{"(%d%d?):(%d%d)","(%d+)"}}
        error_syn("?")
        end
        sw("^%s*") until sw:finish()
    --else print("$Iso(Date|Time|Zone)")
    end
    -- if date is given, it must be complete year, month & day
    if (not y and not h) or ((m and not d) or (d and not m)) or ((m and w) or (m and j) or (j and w)) then return error_inv("!") end
    -- fix month
    if m then m = m - 1 end
    -- fix year if we are on BCE
    if e and e < 0 and y > 0 then y = 1 - y end
    --  create date object
    dn = (y and ((w and makedaynum_isoywd(y, w, u)) or (j and makedaynum(y, 0, j)) or makedaynum(y, m, d))) or DAYNUM_DEF
    df = makedayfrc(h or 0, r or 0, s or 0, 0) + ((z or 0) * TICKSPERMIN)
    --print("Zone",h,r,s,z,m,d,y,df)
    return date_new(dn, df) -- no need to :normalize();
end

local function date_fromtable(v)
    local y, m, d = fix(v.year), getmontharg(v.month), fix(v.day)
    local h, r, s, t = tonumber(v.hour), tonumber(v.min), tonumber(v.sec), tonumber(v.ticks)
    -- atleast there is time or complete date
    if (y or m or d) and (not (y and m and d)) then return error("incomplete table") end
    return (y or h or r or s or t) and date_new(y and makedaynum(y, m, d) or DAYNUM_DEF, makedayfrc(h or 0, r or 0, s or 0, t or 0))
end

local tmap = {
    ['number'] = function(v) return date_epoch:copy():addseconds(v) end,
    ['string'] = function(v) return date_parse(v) end,
    ['boolean'] = function(v) return date_fromtable(osdate(v and "!*t" or "*t")) end,
    ['table'] = function(v) local ref = getmetatable(v) == dobj; return ref and v or date_fromtable(v), ref end
}
local function date_getdobj(v)
    local o, r = (tmap[type(v)] or fnil)(v);
    return (o and o:normalize() or error "invalid date time value"), r -- if r is true then o is a reference to a date obj
end

--#end -- not DATE_OBJECT_AFX
local function date_from(...)
    local arg = pack(...)
    local y, m, d = fix(arg[1]), getmontharg(arg[2]), fix(arg[3])
    local h, r, s, t = tonumber(arg[4] or 0), tonumber(arg[5] or 0), tonumber(arg[6] or 0), tonumber(arg[7] or 0)
    if y and m and d and h and r and s and t then
        return date_new(makedaynum(y, m, d), makedayfrc(h, r, s, t)):normalize()
    else
        return date_error_arg()
    end
end

--[[ THE DATE OBJECT METHODS ]] --
function dobj:normalize()
    local dn, df = fix(self.daynum), self.dayfrc
    self.daynum, self.dayfrc = dn + floor(df / TICKSPERDAY), mod(df, TICKSPERDAY)
    return (dn >= DAYNUM_MIN and dn <= DAYNUM_MAX) and self or error("date beyond imposed limits:" .. self)
end

function dobj:getdate() local y, m, d = breakdaynum(self.daynum) return y, m + 1, d end

function dobj:gettime() return breakdayfrc(self.dayfrc) end

function dobj:getclockhour() local h = self:gethours() return h > 12 and mod(h, 12) or (h == 0 and 12 or h) end

function dobj:getyearday() return yearday(self.daynum) + 1 end

function dobj:getweekday() return weekday(self.daynum) + 1 end

-- in lua weekday is sunday = 1, monday = 2 ...

function dobj:getyear() local r, _, _ = breakdaynum(self.daynum) return r end

function dobj:getmonth() local _, r, _ = breakdaynum(self.daynum) return r + 1 end

-- in lua month is 1 base
function dobj:getday() local _, _, r = breakdaynum(self.daynum) return r end

function dobj:gethours() return mod(floor(self.dayfrc / TICKSPERHOUR), HOURPERDAY) end

function dobj:getminutes() return mod(floor(self.dayfrc / TICKSPERMIN), MINPERHOUR) end

function dobj:getseconds() return mod(floor(self.dayfrc / TICKSPERSEC), SECPERMIN) end

function dobj:getfracsec() return mod(floor(self.dayfrc / TICKSPERSEC), SECPERMIN) + (mod(self.dayfrc, TICKSPERSEC) / TICKSPERSEC) end

function dobj:getticks(u) local x = mod(self.dayfrc, TICKSPERSEC) return u and ((x * u) / TICKSPERSEC) or x end

function dobj:getweeknumber(wdb)
    local wd, yd = weekday(self.daynum), yearday(self.daynum)
    if wdb then
        wdb = tonumber(wdb)
        if wdb then
            wd = mod(wd - (wdb - 1), 7) -- shift the week day base
        else
            return date_error_arg()
        end
    end
    return (yd < wd and 0) or (floor(yd / 7) + ((mod(yd, 7) >= wd) and 1 or 0))
end

function dobj:getisoweekday() return mod(weekday(self.daynum) - 1, 7) + 1 end

-- sunday = 7, monday = 1 ...
function dobj:getisoweeknumber() return (isowy(self.daynum)) end

function dobj:getisoyear() return isoy(self.daynum) end

function dobj:getisodate()
    local w, y = isowy(self.daynum)
    return y, w, self:getisoweekday()
end

function dobj:setisoyear(y, w, d)
    local cy, cw, cd = self:getisodate()
    if y then cy = fix(tonumber(y)) end
    if w then cw = fix(tonumber(w)) end
    if d then cd = fix(tonumber(d)) end
    if cy and cw and cd then
        self.daynum = makedaynum_isoywd(cy, cw, cd)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:setisoweekday(d) return self:setisoyear(nil, nil, d) end

function dobj:setisoweeknumber(w, d) return self:setisoyear(nil, w, d) end

function dobj:setyear(y, m, d)
    local cy, cm, cd = breakdaynum(self.daynum)
    if y then cy = fix(tonumber(y)) end
    if m then cm = getmontharg(m) end
    if d then cd = fix(tonumber(d)) end
    if cy and cm and cd then
        self.daynum = makedaynum(cy, cm, cd)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:setmonth(m, d) return self:setyear(nil, m, d) end

function dobj:setday(d) return self:setyear(nil, nil, d) end

function dobj:sethours(h, m, s, t)
    local ch, cm, cs, ck = breakdayfrc(self.dayfrc)
    ch, cm, cs, ck = tonumber(h or ch), tonumber(m or cm), tonumber(s or cs), tonumber(t or ck)
    if ch and cm and cs and ck then
        self.dayfrc = makedayfrc(ch, cm, cs, ck)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:setminutes(m, s, t) return self:sethours(nil, m, s, t) end

function dobj:setseconds(s, t) return self:sethours(nil, nil, s, t) end

function dobj:setticks(t) return self:sethours(nil, nil, nil, t) end

function dobj:spanticks() return (self.daynum * TICKSPERDAY + self.dayfrc) end

function dobj:spanseconds() return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERSEC end

function dobj:spanminutes() return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERMIN end

function dobj:spanhours() return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERHOUR end

function dobj:spandays() return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERDAY end

function dobj:addyears(y, m, d)
    local cy, cm, cd = breakdaynum(self.daynum)
    if y then y = fix(tonumber(y)) else y = 0 end
    if m then m = fix(tonumber(m)) else m = 0 end
    if d then d = fix(tonumber(d)) else d = 0 end
    if y and m and d then
        self.daynum = makedaynum(cy + y, cm + m, cd + d)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:addmonths(m, d)
    return self:addyears(nil, m, d)
end

local function dobj_adddayfrc(self, n, pt, pd)
    n = tonumber(n)
    if n then
        local x = floor(n / pd);
        self.daynum = self.daynum + x;
        self.dayfrc = self.dayfrc + (n - x * pd) * pt;
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:adddays(n) return dobj_adddayfrc(self, n, TICKSPERDAY, 1) end

function dobj:addhours(n) return dobj_adddayfrc(self, n, TICKSPERHOUR, HOURPERDAY) end

function dobj:addminutes(n) return dobj_adddayfrc(self, n, TICKSPERMIN, MINPERDAY) end

function dobj:addseconds(n) return dobj_adddayfrc(self, n, TICKSPERSEC, SECPERDAY) end

function dobj:addticks(n) return dobj_adddayfrc(self, n, 1, TICKSPERDAY) end

local tvspec = {
    -- Abbreviated weekday name (Sun)
    ['%a'] = function(self) return sl_weekdays[weekday(self.daynum) + 7] end,
    -- Full weekday name (Sunday)
    ['%A'] = function(self) return sl_weekdays[weekday(self.daynum)] end,
    -- Abbreviated month name (Dec)
    ['%b'] = function(self) return sl_months[self:getmonth() - 1 + 12] end,
    -- Full month name (December)
    ['%B'] = function(self) return sl_months[self:getmonth() - 1] end,
    -- Year/100 (19, 20, 30)
    ['%C'] = function(self) return fmt("%.2d", fix(self:getyear() / 100)) end,
    -- The day of the month as a number (range 1 - 31)
    ['%d'] = function(self) return fmt("%.2d", self:getday()) end,
    -- year for ISO 8601 week, from 00 (79)
    ['%g'] = function(self) return fmt("%.2d", mod(self:getisoyear(), 100)) end,
    -- year for ISO 8601 week, from 0000 (1979)
    ['%G'] = function(self) return fmt("%.4d", self:getisoyear()) end,
    -- same as %b
    ['%h'] = function(self) return self:fmt0("%b") end,
    -- hour of the 24-hour day, from 00 (06)
    ['%H'] = function(self) return fmt("%.2d", self:gethours()) end,
    -- The  hour as a number using a 12-hour clock (01 - 12)
    ['%I'] = function(self) return fmt("%.2d", self:getclockhour()) end,
    -- The day of the year as a number (001 - 366)
    ['%j'] = function(self) return fmt("%.3d", self:getyearday()) end,
    -- Month of the year, from 01 to 12
    ['%m'] = function(self) return fmt("%.2d", self:getmonth()) end,
    -- Minutes after the hour 55
    ['%M'] = function(self) return fmt("%.2d", self:getminutes()) end,
    -- AM/PM indicator (AM)
    ['%p'] = function(self) return sl_meridian[self:gethours() > 11 and 1 or -1] end, --AM/PM indicator (AM)
    -- The second as a number (59, 20 , 01)
    ['%S'] = function(self) return fmt("%.2d", self:getseconds()) end,
    -- ISO 8601 day of the week, to 7 for Sunday (7, 1)
    ['%u'] = function(self) return self:getisoweekday() end,
    -- Sunday week of the year, from 00 (48)
    ['%U'] = function(self) return fmt("%.2d", self:getweeknumber()) end,
    -- ISO 8601 week of the year, from 01 (48)
    ['%V'] = function(self) return fmt("%.2d", self:getisoweeknumber()) end,
    -- The day of the week as a decimal, Sunday being 0
    ['%w'] = function(self) return self:getweekday() - 1 end,
    -- Monday week of the year, from 00 (48)
    ['%W'] = function(self) return fmt("%.2d", self:getweeknumber(2)) end,
    -- The year as a number without a century (range 00 to 99)
    ['%y'] = function(self) return fmt("%.2d", mod(self:getyear(), 100)) end,
    -- Year with century (2000, 1914, 0325, 0001)
    ['%Y'] = function(self) return fmt("%.4d", self:getyear()) end,
    -- Time zone offset, the date object is assumed local time (+1000, -0230)
    ['%z'] = function(self) local b = -self:getbias(); local x = abs(b); return fmt("%s%.4d", b < 0 and "-" or "+", fix(x / 60) * 100 + floor(mod(x, 60))) end,
    -- Time zone name, the date object is assumed local time
    ['%Z'] = function(self) return self:gettzname() end,
    -- Misc --
    -- Year, if year is in BCE, prints the BCE Year representation, otherwise result is similar to "%Y" (1 BCE, 40 BCE)
    ['%\b'] = function(self) local x = self:getyear() return fmt("%.4d%s", x > 0 and x or (-x + 1), x > 0 and "" or " BCE") end,
    -- Seconds including fraction (59.998, 01.123)
    ['%\f'] = function(self) local x = self:getfracsec() return fmt("%s%.9f", x >= 10 and "" or "0", x) end,
    -- percent character %
    ['%%'] = function(self) return "%" end,
    -- Group Spec --
    -- 12-hour time, from 01:00:00 AM (06:55:15 AM); same as "%I:%M:%S %p"
    ['%r'] = function(self) return self:fmt0("%I:%M:%S %p") end,
    -- hour:minute, from 01:00 (06:55); same as "%I:%M"
    ['%R'] = function(self) return self:fmt0("%I:%M") end,
    -- 24-hour time, from 00:00:00 (06:55:15); same as "%H:%M:%S"
    ['%T'] = function(self) return self:fmt0("%H:%M:%S") end,
    -- month/day/year from 01/01/00 (12/02/79); same as "%m/%d/%y"
    ['%D'] = function(self) return self:fmt0("%m/%d/%y") end,
    -- year-month-day (1979-12-02); same as "%Y-%m-%d"
    ['%F'] = function(self) return self:fmt0("%Y-%m-%d") end,
    -- The preferred date and time representation;  same as "%x %X"
    ['%c'] = function(self) return self:fmt0("%x %X") end,
    -- The preferred date representation, same as "%a %b %d %\b"
    ['%x'] = function(self) return self:fmt0("%a %b %d %\b") end,
    -- The preferred time representation, same as "%H:%M:%\f"
    ['%X'] = function(self) return self:fmt0("%H:%M:%\f") end,
    -- GroupSpec --
    -- Iso format, same as "%Y-%m-%dT%T"
    ['${iso}'] = function(self) return self:fmt0("%Y-%m-%dT%T") end,
    -- http format, same as "%a, %d %b %Y %T GMT"
    ['${http}'] = function(self) return self:fmt0("%a, %d %b %Y %T GMT") end,
    -- ctime format, same as "%a %b %d %T GMT %Y"
    ['${ctime}'] = function(self) return self:fmt0("%a %b %d %T GMT %Y") end,
    -- RFC850 format, same as "%A, %d-%b-%y %T GMT"
    ['${rfc850}'] = function(self) return self:fmt0("%A, %d-%b-%y %T GMT") end,
    -- RFC1123 format, same as "%a, %d %b %Y %T GMT"
    ['${rfc1123}'] = function(self) return self:fmt0("%a, %d %b %Y %T GMT") end,
    -- asctime format, same as "%a %b %d %T %Y"
    ['${asctime}'] = function(self) return self:fmt0("%a %b %d %T %Y") end,
}
function dobj:fmt0(str) return (gsub(str, "%%[%a%%\b\f]", function(x) local f = tvspec[x]; return (f and f(self)) or x end)) end

function dobj:fmt(str)
    str = str or self.fmtstr or fmtstr
    return self:fmt0((gmatch(str, "${%w+}")) and (gsub(str, "${%w+}", function(x) local f = tvspec[x]; return (f and f(self)) or x end)) or str)
end

function dobj.__lt(a, b) if (a.daynum == b.daynum) then return (a.dayfrc < b.dayfrc) else return (a.daynum < b.daynum) end end

function dobj.__le(a, b) if (a.daynum == b.daynum) then return (a.dayfrc <= b.dayfrc) else return (a.daynum <= b.daynum) end end

function dobj.__eq(a, b) return (a.daynum == b.daynum) and (a.dayfrc == b.dayfrc) end

function dobj.__sub(a, b)
    local d1, d2 = date_getdobj(a), date_getdobj(b)
    local d0 = d1 and d2 and date_new(d1.daynum - d2.daynum, d1.dayfrc - d2.dayfrc)
    return d0 and d0:normalize()
end

function dobj.__add(a, b)
    local d1, d2 = date_getdobj(a), date_getdobj(b)
    local d0 = d1 and d2 and date_new(d1.daynum + d2.daynum, d1.dayfrc + d2.dayfrc)
    return d0 and d0:normalize()
end

function dobj.__concat(a, b) return tostring(a) .. tostring(b) end

function dobj:__tostring() return self:fmt() end

function dobj:copy() return date_new(self.daynum, self.dayfrc) end

--[[ THE LOCAL DATE OBJECT METHODS ]] --
function dobj:tolocal()
    local dn, df = self.daynum, self.dayfrc
    local bias = getbiasutc2(self)
    if bias then
        -- utc = local + bias; local = utc - bias
        self.daynum = dn
        self.dayfrc = df - bias * TICKSPERSEC
        return self:normalize()
    else
        return nil
    end
end

function dobj:toutc()
    local dn, df = self.daynum, self.dayfrc
    local bias = getbiasloc2(dn, df)
    if bias then
        -- utc = local + bias;
        self.daynum = dn
        self.dayfrc = df + bias * TICKSPERSEC
        return self:normalize()
    else
        return nil
    end
end

function dobj:getbias() return (getbiasloc2(self.daynum, self.dayfrc)) / SECPERMIN end

function dobj:gettzname()
    local _, tvu, _ = getbiasloc2(self.daynum, self.dayfrc)
    return tvu and osdate("%Z", tvu) or ""
end

--#if not DATE_OBJECT_AFX then
function date.time(h, r, s, t)
    h, r, s, t = tonumber(h or 0), tonumber(r or 0), tonumber(s or 0), tonumber(t or 0)
    if h and r and s and t then
        return date_new(DAYNUM_DEF, makedayfrc(h, r, s, t))
    else
        return date_error_arg()
    end
end

function date:__call(...)
    local arg = pack(...)
    if arg.n > 1 then return (date_from(...))
    elseif arg.n == 0 then return (date_getdobj(false))
    else local o, r = date_getdobj(arg[1]); return r and o:copy() or o
    end
end

date.diff = dobj.__sub

function date.isleapyear(v)
    local y = fix(v);
    if not y then
        y = date_getdobj(v)
        y = y and y:getyear()
    end
    return isleapyear(y + 0)
end

function date.epoch() return date_epoch:copy() end

function date.isodate(y, w, d) return date_new(makedaynum_isoywd(y + 0, w and (w + 0) or 1, d and (d + 0) or 1), 0) end

-- Internal functions
function date.fmt(str) if str then fmtstr = str end; return fmtstr end

function date.daynummin(n) DAYNUM_MIN = (n and n < DAYNUM_MAX) and n or DAYNUM_MIN return n and DAYNUM_MIN or date_new(DAYNUM_MIN, 0):normalize() end

function date.daynummax(n) DAYNUM_MAX = (n and n > DAYNUM_MIN) and n or DAYNUM_MAX return n and DAYNUM_MAX or date_new(DAYNUM_MAX, 0):normalize() end

function date.ticks(t) if t then setticks(t) end return TICKSPERSEC end

--#end -- not DATE_OBJECT_AFX

local tm = osdate("!*t", 0);
if tm then
    date_epoch = date_new(makedaynum(tm.year, tm.month - 1, tm.day), makedayfrc(tm.hour, tm.min, tm.sec, 0))
    -- the distance from our epoch to os epoch in daynum
    DATE_EPOCH = date_epoch and date_epoch:spandays()
else -- error will be raise only if called!
date_epoch = setmetatable({}, { __index = function() error("failed to get the epoch date") end })
end

--#if not DATE_OBJECT_AFX then
return date
--#else
--$return date_from
--#end
